The present invention relates to electrical switchgear. More particularly, the present invention relates to an arc chute assembly.
Circuit breakers and other electrical switching apparatuses typically include a set of stationary electrical contacts and a set of moveable electrical contacts. The stationary and moveable contacts are in physical contact with one another when it is desired that the circuit breaker provide electrical current to a load. However, when it becomes necessary to interrupt the circuit the moveable contacts are moved away from the stationary contacts, thus removing the moveable contacts from physical contact with the stationary contacts and creating a space there between. This may result in the formation of an electrical arc beginning at the time the contacts are separated.
In these particular instances, electrical arcs (also known as “arc discharges”) are undesirable for a number of reasons. First, they provide a pathway for current to flow through the circuit breaker to a load when it is desired that the load be isolated from such current. Additionally, the electrical arc extending between the contacts often results in vaporization or sublimation of the contact material itself, eventually resulting in destruction or pitting of contacts.
As a result, manufactures of breakers and switching gear have developed mechanisms to facilitate quenching of this undesirable arc discharge. For example, early manufactures used a method of immersing the contact material in an oil, or inert gas, while others created a vacuum to quench arcing. More recently, the development of arc chutes has been a preferred method to quench undesirable arcing.
For example, U.S. Pat. No. 6,703,576 provides an arc chute having a main valve formed by a flexible sheet member that is mounted over a gas opening of the arc chamber structure by extensions on arc plates that form guides received in elongated slots in the ends of the flexible sheet member. The force generated by high pressure gas in the arc chamber on the center of the flexible sheet member causes it to bow allowing arc gases to escape laterally as the ends of the flexible sheet member are drawn towards each other.
Another exemplary breaker assembly including an arc chute is described in U.S. Patent Application US20070062912A1, which comprises an arc chute having two side parallel flanges, a rear wall, and a bottom arcing horn made of conducting material, electrically connected to the stationary contact part. The bottom arcing horn is surrounded by a periphery made of gas-generating material. The arc chute comprises a stack of separators at least two of which separators comprise a notch, at least one regenerating separator placed parallel to the bottom arcing horn, the at least one separator comprising at least one metallic surface covering at least half of the notches in the longitudinal mid-plane.